While the inventive principles of the present invention are applicable to a variety of electrosurgical instruments, as a person skilled in the art will readily appreciate, for purposes of illustration and not limitation, the present invention will be described in reference to one possible embodiment, namely a resectoscope.
Generally, resectoscopes comprise a hollow sheath, a working element, a telescope and an electrode. The working element generally has a guide block that can slide or move, such as by a rack and pinion mechanism or spring, to move the electrode relative to the telescope. The guide block generally has a hole or connector for receiving a portion of the electrode and another hole for receiving an electric plug. The electric plug supplies electricity to the electrode for resection or the like. U.S. Pat. No. 4,538,610 to Kubota shows one type of resectoscope having a guide block or movable member and an extending connecting part. U.S. Pat. No. 4,149,538 to Mrava et al shows a resectoscope having a slide portion with a receptacle or channel for receiving the plug of an electrical lead (not shown). However, problems exist with these and other prior art devices.
There are generally two types of instruments used in electrosurgery. Monopolar devices employ a single electrode at the operative end of the instrument and an electrode return plate generally located under and in contact with the patient. The electrode plate constitutes a second dispersive electrode so that electrical current used to ablate or alter tissue passes through the patient.
Bipolar devices employ two electrodes spaced closely together at the operative end of the instrument so that the flow of current is confined to the tissue in close proximity to the electrodes. Bipolar devices require a saline or other electrolytic environment in order to provide a conductive path between the electrodes. One problem with bipolar devices is that the electrical connections must be electrically isolated from the saline environment in order to prevent electrical short-circuiting. Short-circuiting will reduce the effectiveness of the resectoscope for its intended function. In particular, the electric plug or bipolar cord must be sealingly engaged with the device. In order to provide a sealed connection prior art bipolar devices have integrated the bipolar cord into the device as a single unit. However, such an integrated design presents difficulties in maintaining a seal between the electrode and working element that is both leak proof and of low frictional drag on the electrode when it is mechanically moved in and out of the sheath by the user.
During an operation on a patient, the doctor or operator must feel confident and secure with his instrument. In the past, various different manufacturers of medical instruments produced different designs of instruments having electric cords connected at various different locations on their individual instruments. Doctors who have developed a preference for a certain type of instrument may feel uncomfortable in changing to other types or makes of the same instrument merely because of the change in orientation of the electrical wire such as in a resectoscope. Thus, a user who is comfortable with a resectoscope having a connector located on the top of the resectoscope such as that shown, for example, in Kubota ('610), might feel uncomfortable using a resectoscope in which the electric power cord extends downward rather than upward such as shown, for example, in Mrava et al ('538). In addition, the resectoscope shown and described in Mrava et al ('538) would probably be uncomfortable for a left handed user.
U.S. Pat. No. 4,917,621 to Grossi et al, the subject matter of which is herein incorporated by reference, discloses a resectoscope having a disconnectable electrical plug that can be connected to the device on either a first or a second side. However, the electrical plug does not sealingly mate with the device. Accordingly, there is a need for a medical instrument having a power cord system that is adaptable to accommodate different user preferences.
In addition, there is a need for improved disposable active cords that are convenient to use and that provide more optimal sealing to protect against short-circuiting.